a b s t r a c t A carbohydrate–aromatic complex, methyl a-L-fucopyranoside Á toluene, which provides a model for probing the physical basis of carbohydrate–protein 'stacking' interactions, has been created in a molec-ular beam and probed through IR ion dip spectroscopy in the CH and OH regions. The results are inter-preted in the light of DFT calculations using the MO5-2X functional. They indicate the creation of stacked structures with the aromatic molecule bonded either to the upper or to the lower face of the pyranoside ring, through CH 3,4 –p (upper) or CH 1 –p (lower) interactions leading to binding energies 618 kJ mol À1 .